The 20-year-old defender was playing on loan at non-league Eastbourne Borough eight months before his move to Arsenal last June.
"I didn't start how I would have liked to, but an honest assessment would be that as I have progressed, got more minutes under my belt and trained with the boys I definitely feel like I have improved a lot," Jenkinson told Arsenal Player.
"It was a very steep learning curve for me. I believed I was capable of playing at the highest level, and sometimes it is about getting seen by the right people at the right time.
"I have had some tough times but I feel like I have come out of it a bigger and better person, and a better player.
"In a football career you are going to have ups and downs and tough times, but people have told me it is about how you respond to those tough times that will make or break you as a footballer."